1. Field of the Invention
The present invention relates to an automatic running work vehicle, and more particularly to such a work vehicle wherein both front wheels and rear wheels can be steered and which is equipped with a follower sensor for detecting the boundary between a worked area and an unworked area so as to run automatically along the boundary.
2. Description of the Prior Art
Such automatic running work vehicles heretofore known are adapted for follower control by the above-mentioned follower sensor to steer the steering wheels based on the result of detection of the boundary and automatically correct the running direction. For example, when both front and rear wheels are steered toward the same direction, the vehicle body can be translated without changing the orientation of the vehicle body, so that during the follower control, the running direction can be corrected while permitting the vehicle body to retain straightforwardness with a reduced likelihood of the vehicle body zigzagging. It is therefore thought useful to adapted both front and rear wheels for steering control.
However, even in the follower control wherein both the front and rear wheels are steered, the orientation of the vehicle body is likely to spontaneously deviate from the direction of the boundary owing to the slippage of the wheels. Thus, there is the drawback that the running direction can not be corrected efficiently to drive the vehicle along the boundary merely by steering the vehicle body for translation.